Locking means for workholders or jigs



Patented Aug. 30, 1932 UNITED STATES PATENT OFFICE EDWARD L. GREER, OF HIGHLAND PARK, AND KARL F. MARX, OF DEARBORN',y

MICHIGAN i LOCKING MEANS FOB WORKHOLDERS OR J'IGS Application filed February 12, 1931. Serial No. 515,390.

The present invention pertains to a novel frictional locking mechanism of a type particularly adapted for use in combination with various types of work holders such as quick acting vises or jigs.

Theprimary object of the present invention is to devise a locking mechanism which when mounted upon the operating shaft of a quick acting vise or jig serves as means for rotating said shaftV to exert clamping pressure upon the work clamping head, said mechanism comprising parts which co-act in a. manner to permit a predetermined amount of pressure to be exerted upon said shaft and clamping head and then serving to frictionally prevent rotation of said shaft either by pressure of the operating handle or back pressure exerted by the clamping head upon Jthe shaft.

Another object of the present invention is to devise a locking mechanism which may be constructed as a separate unit applicable to any shaft wherein it is desired to rotate the same until a predetermined pressure is reached, said mechanism serving as a locking'nieans for holding said shaft at any stage of revolution when the predetermined pressure is reached. The device serves as aV means for rotating the shaft in either direction bfut ythe device rather than rotate the shaft.-

`With the above and other ends in view the `invention .consists in matters hereinafter set forth and more particularly pointed out in the appended claims, reference 'being had to the accompanying drawing, in which Figure l is a transverse cross' sectional view through the present locking mechanism, the View being taken substantially on the line A-A of Fig. 2;

Fig. 2 is a longitudinal cross sectional view taken on the line B-B of Fig. l, and t Y Fig.` 3 is a side elevation of a conventional jig illustrating the attachment of the pres-ent device thereto.

Like characters of reference are employed throughout to designate the corresponding parts. j Y

The numerall indicates the supporting or outer casing having holes 2 through which bolts are passed to secure the casing to the side Wall of the 14 or any other similar holding device. rlfhe casing l is provided with a circular bore l through which the jig operating shaft 7 projects.

Loosely surrounding the portion of the shaft 7 which projects outwardly through the casing l is an actuating member 5, preferably formed of angular shape such as a hexagonal nut to receive an operating handle or wrench l2. The actuating member 5 is retained from slipping o the shaft 7 by the washer l1 which is secured to the end of the shaft by means of a screw 8, screwthreaded into a suitable bore provided in said shaft.

The outside ldiameter of the actuating member 5 is greater than the diameter of the bore l and therefore covers the end of the same as clearly illustrated in Fig. 2 of the drawing. Formed on the inside face of the actuating member is a flat walled projection 5 which projects into the bore l for a purpose which will become apparent as the description progresses.

A block 6 is mounted upon the shaft 7 within the bore l and is keyed as at 9 to rotate j therewith7 the block having flattened walls 6. Resting against the flat faces 6 are wedges 4 which serve to normally hold a pair of segments 3 in Contact with the wall of the bore l, the segments having their outer walls curved with the same radius as the bore 1.

The wedges 4 are provided with recesses il into which the projection 5 on the actuating member projects7 the recess being formed large enough to provide a slight clearance. In the segments 3 are formed recesses 3 constructed to provide a greater clearance on either side of the flattened projection 5 than is provided in the wedge. Theprojection 5 is bored as at l0 and springs 10 are j the sprinlg The rotation of the handle rotates the actuating member 5 and the side walls of the projection 5 rotates the wedges 4 and segments 3, the wedges causing the block 6 to be rotated and because it is keyed to the shaft the latter rotates also. It will be noted however that the rotation is imparted to the segments by l() and therefore when the resistance kon t e shaft 7 becomes greaterthan the pressure of the spring the latter is compressed and the rotative pressure on the actuating member is then imparted upon the side walls of the recesses 4 in the wedges which are thereby moved in a manner to force the segments outwardly against the wall of thebore 1 and thusV lock the segments, wedges, block 6 and the shaft 7 against further rotation.

' In order to release the locking mechanism pressure is exerted upon the handle 12 in the opposite direction and the projection 5engages the opposite side wall of the recesses 4 causing the wedges to be moved outwardly in a manner permitting the outward or locking pressure of the wedges against the segments to be released. The direction in which the small ends of the wedges are pointed governs the direction in which the operating handle must be turned in order to cause the locking edges. It becomes apparent, therefore, that the device is adaptable to either clockwise or contra-clockwise turning operating handles by merely reversing the direction of the small ends of the wedges.

Although a specific embodiment of the present invention has been illustrated and described it is to be understood that various changes may be made in the details of construction without departing from the spirit of the invention as defined inthe appended claims, and such changes are contemplated.

What we claim is: Y

1. The combination with a shaft upon which back pressure is exerted, of an actuating member vfreely mounted upon said shaft, a member non-rotatably mounted upon said shaft, a stationary casing mounted to surround said shaft, segments mounted in said casing, wedges interposed between said segments and said non-rotatable member, said wedges and segments being enga-ged by said `actuating member in a manner whereby excessive rotative pressure on said actuating ymember causes said wedges to force said segments tightly in contact with said'casing when the resistance against rotation on'said shaft reaches a certain degree.

2. The` combination with a shaft upon which back pressure is exerted, of a circular fixed casing surrounding an end portion yof said shaft, a block secured to said shaft to rotate therewith, wedges contacting with the Y sides of said block, segments interposed between said wedges and the wall of said casing, and an actuating member loosely mounted upon said shaft and adapted to engage said wedges and segments to impart rotation to said block and thereby rotate said shaft.

3. The combination with a shaft upon which bacl pressure is exerted, of a station'- ary casing surrounding the end of said shaft, afiat sided member mounted upon said shaft to rotate therewith, wedges contacting with said flat sided member, segments contacting with said wedges and the inner wall of said casing, and an actuating member projecting into recesses formed in said wedges and segments, said actuating member having springs mounted .therein to engage said segments whereby rotation of said actuating member causes rotation of said segments, wedges, flatsided member and shaft.

4. The combination with a shaft upon which back pressure is exerted, of a statlonary casing surrounding the end of said shaft, a flat sided member mounted upon said shaft to rotate therewith, wedges contacting with said fiat sided member," segments Contactin with said wedges and the inner wall of sai ca-sing,recesses formed ,in said wedges, recesses formed in said segments of greater widthl of said first named recesses, an actuating member projecting into said recesses in a manner permitting lost motion before engaging the side walls of said recess to impart rotation from said actuating member to said segments, wedges, flat sided member and shaft, and springs carried by said actuating member to engage said segments in a manner whereby excessive back pressure on said shaft causes said springs to be compressed and causes said actuating member to move' said Wedges in a manner to force said segments outwardly into contact with said stationary caslng.

5. The combination with a rotatable shaft upon which back pressure is exerted, of acas- ,ing having va circular bore non-rotatably secured relative to said casing, an actuating member mounted on said shaft to rotate freely thereon and having projections extending into said circular bore, segments mounted in said circular bore, a block keyed to said shaft to rotate therewith, wedges. interposed between said segments and said block, recesses formed in said wedges to'receive the projecting portion of said actuating member, recesses 

